Some problems occur when your Internet security program was set to trust the previous version of Firefox, but no longer recognizes your updated version as trusted. Now how to fix the problem: To allow Firefox to connect to the Internet again;

• Make sure your Internet security software is up-to-date (i.e. you are running the latest version).
• Remove Firefox from your program's list of trusted or recognized programs. For detailed instructions, see

Configure firewalls so that Firefox can access the Internet. {web link}

Start Firefox in Safe Mode {web link}

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

Hi Fred,

Thanks for your willingness to help. The problem has been solved, but not because of your advise. It turned out that Firefox did open, but on my second monitor. This second monitor was off, so I did not see that Firefox actually opened. I did not know things worked like that when you're working with more than 1 monitor. Apparently you have to drag the browser back to your primary monitor after you have opened it on a secondary monitor (even after you have reboot the pc). Thanks again though for trying to help me.

Regards,

Richard

That was very good work. Well Done. Please flag your last post as Solved Problem as this can help others with similar problems.